In device fabrication, one or more device layers are formed on a substrate. The layers are sequentially deposited and patterned to create features on the surface of the substrate. The layers can be patterned individually and/or as a combination of layers to form the desired features. The features serve as components that perform the desired functions, creating the device.
One type of device which is of particular interest is a light emitting diode (LED). LEDs can have a variety of applications. For example, a plurality of LED cells or pixels can be formed on a substrate to create a pixelated LED device for use as a display, such as a flat panel display (FPD) for telephones, computer displays, TV screens and the like.
Typically, an LED pixel comprises one or more functional layers sandwiched between two electrodes to form a functional stack. Charge carriers are injected from both electrodes. These charge carriers recombine in the functional layer or layers, causing visible radiation to emit. Recently, significant advances have been made utilizing organic functional layers to form organic light emitting diodes (OLEDs).
OLED pixels are very sensitive to the environment. Exposure to moisture and/or air causes rapid degradation of the OLED, creating reliability problems. Some of the substances used to build the layers are sensitive organic compounds and some reactive metals like Calcium and Magnesium. These materials are extremely susceptible to damage caused by oxidation in the presence of oxygen and/or moisture. Thus, a package which adequately protects the OLED from the environment is needed. Further, the package should be cost effective and conducive to high throughput to reduce the overall manufacturing cost and time.